illusion

American  

[ih-loo-zhuhn] / ɪˈlu ʒən /

noun

1. something that deceives by producing a false or misleading impression of reality.

   Synonyms:

   chimera, fantasy, aberration

2. the state or condition of being deceived; misapprehension.

3. an instance of being deceived.

4. Psychology. a perception, as of visual stimuli optical illusion, that represents what is perceived in a way different from the way it is in reality.

5. a very thin, delicate tulle of silk or nylon having a cobwebbed appearance, for trimmings, veilings, and the like.

6. Obsolete. the act of deceiving; deception; delusion.

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illusion British  

/ ɪˈluːʒən /

noun

1. a false appearance or deceptive impression of reality

   the mirror gives an illusion of depth

2. a false or misleading perception or belief; delusion

   he has the illusion that he is really clever

3. psychol a perception that is not true to reality, having been altered subjectively in some way in the mind of the perceiver See also hallucination

4. a very fine gauze or tulle used for trimmings, veils, etc

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Related Words

illusion, hallucination, delusion refer to false perceptions or ideas. An illusion is a false mental image produced by misinterpretation of things that actually exist: A mirage is an illusion produced by reflection of light against the sky. A hallucination is a perception of a thing or quality that has no physical counterpart: Under the influence of LSD, Terry had hallucinations that the living-room floor was rippling. A delusion is a persistent false belief: A paranoiac has delusions of persecution.

Other Word Forms

• illusionary adjective
• illusioned adjective

Etymology

Origin of illusion

First recorded in 1300–50; Middle English from Latin illūsiōn- (stem of illūsiō ) “irony, mocking,” equivalent to illūs(us), past participle of illūdere “to mock, ridicule” ( il- il- ¹ + lūd- play ( see ludicrous) + -tus past participle suffix) + -iōn- -ion

Explanation

An illusion is something that isn't real. It may look real, but it's actually fake — just a crafty construction or fantasy. Like the old rabbit-out-of-the-hat trick practiced by magicians around the globe. An illusion is an act of deception. Some optical illusions are pretty cool to watch, but an illusion can also point to an erroneous belief or false perception of reality, which is where you start getting into hallucination territory — seeing things that aren't there. You can give the illusion that you’re fascinated by your professor’s lecture by chewing on your pencil, furrowing your brow, and making sure to nod enthusiastically every so often.

Example Sentences

This is actually something of an optical illusion, for the options are not getting more expensive in terms of price as the earnings date approaches.

From MarketWatch • Apr. 9, 2026

His beauty routine included creams, small rituals in pursuit of an illusion he took seriously.

From BBC • Apr. 4, 2026

We take it day by day, week by week, like adults who have finally accepted that certainty is an illusion.

From Los Angeles Times • Apr. 3, 2026

They explore how Top Model’s central promise—a fast track to a career in the fashion industry—was ultimately an illusion used to make great television at the expense of the contestants.

From Slate • Mar. 31, 2026

Clinging to the illusion of their marriage, she concluded, “Well Ernest I must close my short letter. Hoping to hear from you soon. Good by from your wife, Mollie Burkhart.”

From "Killers of the Flower Moon" by David Grann

Related Words

• confusion
• deception
• delusion
• fantasy
• hallucination
• image
• misconception
• myth
• pipe dream
• semblance